Gyms typically have a limited amount of exercise equipment due to equipment costs and limited space. Gyms often have sets of dumbbells in 10- or 5-pound increments. For example, a gym may have a 40 lb. (18.1 kg) pair of dumbbells and the next heavier dumbbells may be a 45 lb. (20.4 kg) pair of dumbbells. This presents disadvantages because it can decrease the rate of weight progression in training routines that require users to slowly increase resistance. Gym users who rely on dumbbells must make significant gains in strength before progressing to heavier dumbbells. This often results in a user hitting a “plateau” where the user is incapable of safely using a heavier dumbbell (or set of dumbbells). When a person attempts to lift too much weight, he or she can often be injured because free weights are often difficult to control. For example, gyms often have 10-pound increments for dumbbell sets heavier than 100 pounds, so a gym may provide a 100 lb. pair of dumbbells, a 110 lb. pair of dumbbells, and a 120 lb. pair of dumbbells. These 10-pound increments may make it difficult for users to gain strength and may result in injuries.